The version numbers are pretty much meaningless because you get the latest packages anyway by running emerge -u world. So, if I did a 1.1 install and an emerge -u world I would be just as up-to-date as the next guy.

As far as 1.3x goes, those are 'beta' GCC3 releases. When 1.4 comes out, someone will probably figure out how to migrate existing GCC2 systems (1.2 or earlier) to GCC3 (1.3 or later). In any case, don't worry about it; even if you stick with GCC2, you can still use the latest packages...